Trees planted to form a barricade to pollution (2)

About 95 percent of the trees that have been planted are growing well, according to the Beijing Municipal Landscape and Forestry Bureau.

In summer, winds carry dust and sand to the capital, a result of there being large stretches of bare land with little tree cover, Wang said.

As part of the 250-sq-km afforestation project, the district has planted trees on more than 13.8 hectares. Most of them have been planted by highways and railways.

The green guards are expected to help lower the amount of PM2.5, particulate matter with a diameter no bigger than 2.5 micrometers, in the air and reduce the chances Beijing residents have of developing heart and breathing conditions, as well as lung cancer, said Wang Qiuxia, a researcher for Green Beagle, an environmental protection NGO in Beijing.

According to the Beijing Municipal Environmental Protection Bureau, 24.5 percent of PM2.5 contaminants in the capital come from neighboring provinces. Preventing them from coming in will greatly improve the city's air.

The newly planted trees are expected to prevent as much as 2,096 metric tons of dust from getting into the air each year, the bureau said.